Transmissions with power splitting are usually designed with a hydrostatic branch and a mechanical branch, which are summed by means of a summing gear system. Such power-splitting transmissions are known, for example, from DE 10 2007 047 194 A1 and DE 10 2008 001 613 A1. They are also known as CVT devices (Continuously-Variable Transmissions) and are transmissions having two or more driving ranges, which are used inter alia in machine tools and in vehicles. Vehicles made with such transmissions can be driven in the forward direction and in the reverse direction. Within the driving ranges, in each case a transmission ratio of a power-splitting transmission can be adjusted continuously. For this, the hydrostatic branch usually comprises a first hydrostatic unit and a second hydrostatic unit, whose stroke volumes are adjustable.
Disadvantageously, such power-splitting transmissions or transmission devices with secondarily coupled power splitting both entail high production costs and occupy considerable structural fitting space. The combination of these CVT transmissions in the drive-trains of vehicles having drive engines whose drive power is low, is only favored in some cases despite their many operational advantages.